1. Field of the Invention
The present invention relates generally to a waveform shaping apparatus for waveform-shaping a digital signal in the form of a base-band and more particularly is directed to a waveform shaping apparatus having improved precision for correcting distortion.
2. Description of the Prior Art
It is known, in data transmission that, in order to minimize code error due to inter-symbol interference, the waveform has to be equalized, that is, a base-band signal has its waveform shaped such that on a first reference of Nyquest, or on a time axis of an impulse response waveform, the waveform will cross at zero points at equal intervals.
In order to increase the precision for correcting distortion, it is preferable to carry out the waveform shaping by a digital circuit. However, in the case of the prior art waveform shaping apparatus formed of a digital circuit, the result of addition carried out in the waveform shaping apparatus is displaced in the direction of one polarity so that the word length of the given data can not be utilized as effectively as possible. In other words, there is less than full utilization of the entire dynamic range.